George Is in Second Grade and Is Having Trouble

George is in second grade and is having trouble. He frequently is out of his seat, looking at the work of other students and annoying them by making comments. He interrupts the teacher, blurts out answers before she finishes the question, and usually needs directions repeated multiple times. At home, his mother says he is always "on the go." The most likely diagnosis for George is ________

A) conduct disorder.
B) oppositional defiant disorder.
C) separation anxiety disorder.
D) attention-deficit/hyperactivity disorder.